This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 15 |
| 5 | 69 |
| 6 | 389 |
| 7 | 2594 |
| 8 | 19884 |
| 9 | 172328 |
| 10 | 1665838 |
| 11 | 17768938 |
| 12 | 207304278 |
| 13 | 2625854188 |
| 14 | 35886673906 |
| 15 | 526337883960 |
| 16 | 8245960182038 |
| 17 | 137432669700634 |
| 18 | 2427977164711192 |
| 19 | 45322240407942258 |
| 20 | 891337394689531069 |